A COMPARATIVE-STUDY OF THE FATIGUE BEHAVIOR OF GRP HAND LAY-UP AND PULTRUDED PHENOLIC COMPOSITES

This paper presents a study of the fatigue behaviour of E-glass-type f ibre-reinforced phenolic composites manufactured by the pultrusion and the hand lay-up processes, with the main objective of assessing the i nfluence of the manufacturing process on the fatigue life. For the han d lay-up process fatigue data are shown for composites with fibres ali gned in the 0 degrees longitudinal tensile loading directions, 90/0/90 orientations and 0/90/0 fibres with tensile loading applied also in t he longitudinal direction. The results were obtained for two different values of frequency, stress ratio and temperature. In the pultruded s pecimens fatigue life data are presented at room temperature and only one value of stress ratio and frequency. The results were obtained for five sets of manufacturing parameters including a woven-type composit e. With the exception of the woven pultruded specimens, which gave low fatigue strength values, the remaining types of pultruded composite h ave shown adequate fatigue strength values but lower than the results obtained for the longitudinally loaded 0 degrees hand lay-up specimens . The hand-lay-up composite of the unidirectional fibre orientation (0 degrees) have shown higher values of fatigue strength at the elevated temperature of 200 degrees C in comparison with the room temperature values. The variations obtained in fatigue strength amongst the differ ent types of composites are assessed through the analysis of data and also by the failure mechanisms detected by SEM observations.